Two-dimensional modelling of polycrystalline silicon thin film solar cells

In this paper, we present a model for the 2D numerical simulation of polycrystalline silicon solar cells. This model assumes a columnar structure of grain boundaries and a preferential diffusion of dopants formed along grain boundaries during the emitter step process. The simulation results of IQE and I-V parameters are compared to experimental data obtained on n/sup +/pp/sup +/ polycrystalline Si structure, 25 /spl mu/m thick and with 4 /spl mu/m grain size. The theoretical calculations showed a potential of about 10% efficiency with deep emitter diffusion. The limiting parameters like recombination velocity at grain boundaries and phosphorus diffusion depth effects on the I-V characteristic and the internal quantum efficiency are discussed. The effect of the drift-field in the base region on the enhancement of the minority carrier diffusion length is also investigated and discussed.